Tube connector and method of making a connection

ABSTRACT

One embodiment of the invention provides a joining element for joining a tube with a port. The joining element comprises a seal having a bore for accepting the tube, a nut and a ferrule. The ferrule has a bore for accepting the seal and the tube, a retaining member which retains the tube with the ferrule by engaging the tube, and a positive stop which limits engagement of the retaining member and the tube. The nut has a bore for accepting the ferrule and the tube and a bearing surface which engages the positive stop on the ferrule to positively limit engagement of the retaining member and the tube. Still other embodiments provide methods for forming a connection between a tube and a port. One such method comprises inserting the tube into a first member and a second member. The first member is moved with respect to the second member such that the second member is positioned partially within the first member. The first member, the second member and the tube are placed in the port. A mating structure on the first member is mated with a complementary mating structure on the port. The first member is moved with respect to the second member within the port such that a retention member on the second member engages the tube. The action of at least one of the first member and the retention member is positively limited.

This case is a division of U.S. patent application Ser. No. 08/291,001filed Aug. 15, 1994 and now U.S. Pat. No. 5,536,049.

BACKGROUND OF THE INVENTION

Embodiments of the present invention generally relate to a joiningelement for use with a conduit and a method of making a connection withthe joining element. More specifically, embodiments of the presentinvention relate to a connector for joining a tube on an analyticalinstrument and a method for making such a connection.

An analytical instrument may be a complex machine which performs anumber of predetermined tasks. In order to perform these predeterminedtasks, the analytical instrument may have structures dedicated toperforming elements of those tasks. For instance, a biological sampleanalyzer may comprise a fluid system and a detection system. The fluidsystem may provide fluids, such as reagents and the like, to the sample.The sample/reagent mixture may be incubated. After incubation, thesample/reagent mixture may be read by the detection system therebyproviding an operator with desired data.

In order for the analytical instrument to perform according toexpectations, it is desirable that each element of the instrumentfunction optimally. For example, it is desirable that every element ofthe detection system and the fluid system operate in an intendedfashion. If an element of either the detection or fluid system were notto operate as expected, the entire instrument may not function accordingto specifications. This might result in inaccurate data being suppliedto the instrument operator.

Focusing on the fluid system, it may comprise a series of conduits ortubes joined to ports in other structures in the instrument by aconnector. Because the tubes may convey fluid, such as reagents and thelike, from one part of the instrument, such as a stock bottle, to otherparts of the instrument, such as a pump, a dispense head and the like,it is beneficial that no fluid leaks from any of the connections. Somereagents may be expensive, thereby further emphasizing the need to haveno leaks.

The connections between the tubes and the other parts of the instrumentmay be made by connectors which compress the tubes or other structuresin an effort to form a substantially fluid-tight connection. Also, theconnection may be made by a threaded coupling of the connector and theport of the instrument.

Because of their constructions, some connectors may not performaccording to expectations. Connectors that are produced in largequantities may exhibit variations from one connector to another. Thesevariations may compromise the integrity of the connection made betweenthe tube and the instrument, thereby possibly resulting in a fluid leak.

Connectors that utilize a threaded coupling may be sensitive toinstallation forces, such as a torque applied to the connector to engagethreads. In some cases, an installer may apply too much torque, i.e.tighten the connector too much, in an effort to prevent a fluid leak.Over-tightening the connector may cause the tube to collapse to acertain extent. This can inhibit fluid flow through the instrument. Onthe other hand, if the connectors are not sufficiently tightened, theymay leak. Because the connector may not provide the installer with anindication of a proper connection (appropriate tightness), the installermay not know if he has tightened the connector too little or too much.

In some cases, the connectors may loosen over time. In these cases, theconnectors may have to be re-tightened periodically. But, an analyticalinstrument may be quite complex. The connectors may be difficult toreach and therefore difficult to re-tighten. Some connectors may requirea tool for installation and re-tightening which may further complicatemaintenance of the connection and the instrument.

During operation of an analytical instrument, various forces may beapplied to a tube. These forces may try to pull the tube out of aconnector. To reduce the probability that a tube will be pulled out of aconnector, the connector may be provided with a blade-like member. Thisblade-like member is intended to cut into the tube just enough to resistthe tube being pulled out of the connector. However, in some connectors,the distance of the cut into the tube is dependent upon how much theconnector is tightened into the instrument. Therefore, if the installerover-tightens the connector, the blade-like member may cut too far intothe tube, thereby possibly resulting in a leak. Alternatively, if theconnector were insufficiently tightened, then the tube may pull awayfrom the connector and the instrument port, also possibly causing afluid leak.

Additionally, the construction of some connectors may not allow them tobe reused. Removal of an connector from an instrument may damage theconnector beyond repair. Also, the connector may damage the tube to suchan extent that the tube as well as the connector must be replaced. Also,once the connector is disassembled, the individual parts comprising theconnector may be lost.

SUMMARY OF THE INVENTION

One embodiment of the invention provides a joining element for joining atube with a port. The joining element comprises a seal having a bore foraccepting the tube, a nut and a ferrule. The ferrule has a bore foraccepting the seal and the tube, a retaining member which retains thetube with the ferrule by engaging the tube, and a positive stop whichlimits engagement of the retaining member and the tube. The nut has abore for accepting the ferrule and the tube and a bearing surface whichengages the positive stop on the ferrule to positively limit engagementof the retaining member and the tube.

Another embodiment offers a connector for joining a tube with a port.The connector comprises a second member and a first member. The secondmember has a bore for accepting the tube, a retention member forretaining the tube with the second member, and an outer diameter surfacedefined by an outer diameter adjacent the retention member. The firstmember has a bore for accepting the second member and the tube, and aportion for activating the retention member on the second member toretain the tube with the second member, with the portion being definedby an inner diameter. The inner diameter and the outer diameter arepredetermined to positively limit activation of the retention member.

Still other embodiments provide methods for forming a connection betweena tube and a port. One such method comprises inserting the tube into afirst member and a second member. The first member is moved with respectto the second member such that the second member is positioned partiallywithin the first member. The first member, the second member and thetube are placed in the port. A mating structure on the first member ismated with a complementary mating structure on the port. The firstmember is moved with respect to the second member within the port suchthat a retention member on the second member engages the tube. Theaction of at least one of the first member and the retention member ispositively limited.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away expanded perspective view of a tube connectoraccording to an embodiment of the present invention with a tube shown indotted lines;

FIG. 2 is a perspective view of a ferrule comprising the tube connector;

FIG. 3 is a cross sectional view of the ferrule of FIG. 2;

FIG. 4 is a perspective view of a seal comprising the tube connector ofFIG. 1;

FIG. 5 is a cross sectional view of a threaded member comprising thetube connector of FIG. 1;

FIG. 6 is an enlarged portion of FIG. 5; and

FIG. 7 is an enlarged cross sectional view of the tube connectordisposed within a port.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 7 illustrate joining elements or connectors 10 comprisingembodiments of the present invention for joining a conduit or tube 12,shown in dotted lines, to another structure. In an exemplary embodiment,the connector 10 generally includes three elements: a first member ornut 14, a second member or ferrule 18 and a third member or seal 18.While the present invention will be described herein with respect tospecific embodiments, for the sake of clarity of understanding, it is tobe noted that other constructions are also possible. For instance, theseal 18 may be formed integrally with the ferrule 16. In suitableapplications, the ferrule 16 may be provided integrally with the nut 14.Additionally, any suitable combination of elements of the describedembodiments are also possible. Furthermore, while the illustratedembodiment of the connector 10 may be particularly useful for making atube 12 connection in an analytical instrument, other applications ofthe connector 10 are also possible.

An exemplary construction of the nut 14 is shown in FIGS. 1 and 5through 7. Specifically, the nut 14 is generally cylindrical inconfiguration having a through bore 20 for accepting the tube 12. Thebore 20 defines an internal configuration of the nut 14 whichfacilitates gripping of the tube 12, as will be discussed in greaterdetail below. The bore 20 extends from a first end 22 of the nut 14 to asecond end 24 of the nut 14.

In the illustrated embodiment, the first end 22 of the nut 14 isconstructed to facilitate application of an installing force to theconnector 10. In this embodiment, the first end 22 includes an outerdiameter surface 26 bearing a gripping surface or knurl 28 to facilitateinstallation force transfer to the nut 14. Other configurations of thegripping surface are possible. For instance, if it were desirable toinstall the connector 10 with a tool, such as a wrench and the like, thegripping surface may be constructed with a configuration to facilitateforce transfer from the wrench to the nut 14. However, in theillustrated embodiment, the connector 10 is intended to be installed byhand. Thus, the knurl 28 is configured to generate friction between theinstaller's hand and the nut 14. To ease introduction of the tube 12into the bore 20, the first end 22 includes a beveled surface 30. Thesurface 30 is inclined inwardly toward an axis of elongation of the bore20. In this manner, when the end 32 of the tube 12 engages the beveledsurface 30, the end 32, and therefore the tube 12, will be directed intothe bore 20.

The second end 24 of the nut 14 includes a bearing surface 34. Thebearing surface 34 cooperates with structures on the ferrule 16 to forma mechanism for positively limiting constriction of the inner diameterof the tube 12 when the tube 12 is joined by the connector 10. A portionof the outer surface of the nut 14 from a distal end of the knurl 28 toa proximal end of the bearing surface 34 includes structures for matingwith a portion of a body 36 (FIG. 7) to which the tube 12 is to bejoined. In the illustrated embodiment, these mating structures comprisethreads 38. Other mating structures, such as those generating aninterference fit and the like, are also possible.

Adjacent the second end 24, the bore 20 deviates from a substantiallysmooth cylindrical configuration. Specifically, an enlarged diameterportion 40 is located immediately adjacent the second end 24. The lengthof the inner diameter of the nut 14 at this portion 40 is substantiallysimilar to the length of an outer diameter of an entering portion 42 ofthe ferrule 16 so that the entering portion 42 of the ferrule 16 fitsdiametrically within the enlarged portion 40. The enlarged portion 40extends a limited distance axially along the nut 14.

A relatively reduced diameter portion 44 is located on the nut 14proximally of the portion 40. The inner diameter of the portion 44 issmaller than the outer diameter of the entering portion 42 of theferrule 16. The portion 44 cooperates with the ferrule 16 for retainingthe tube 12 against axial movement (pull out) with respect to theconnector 10 as will be discussed in greater detail later. A beveledportion 46 connects the enlarged portion 40 to the reduced portion 44.The beveled portion 46 slopes from the portion 40 to the portion 44 sothat the entering portion 42 of the ferrule 16 moves from the portion 40to the portion 44 upon relative axial movement between the nut 14 andthe ferrule 16 when the connector 10 is installed. The portion 44 alsoextends a limited distance axially along the nut 14. The portion 44 isjoined to a tube engaging portion 48 of the bore 20 by another beveledportion 50. The portion 48 has a diameter substantially equal to anouter diameter of the tube 12.

An exemplary embodiment of the ferrule 16 is shown in FIGS. 1 through 3and 7. The ferrule 16 generally comprises a relatively large outerdiameter portion 52 and the entering portion 42. The portion 42 of theferrule 16 is substantially hollowly cylindrical interruptedcircumferentially by at least one axially extending slot 56. In theillustrated embodiment, there are two such slots 56 spaced equidistantlycircumferentially on the portion 42. The slot 56 extends along almostthe entire axial length of the portion 42. The slot 56 cooperates withthe portion 44 on the nut 14 and forms part of a mechanism for resistingpull out of the tube 12.

The slot 56 is bounded circumferentially or longitudinally on theportion 42 by a pair of reduced sections 58A and 58B on the portion 42.There is one set of reduced sections 58A and 58B for each slot 56 on theportion 42. The reduced sections 58A and 58B may have an outer diametersmaller than the outer diameter of the remainder of the portion 42 ormay be substantially planar extending beneath a projection of the outersurface of the remainder of the portion 42. The sections 58A and 58Breduce contact between the ferrule 16 and the nut 14 such thatrotational movement of the ferrule 16, upon rotational movement of thenut 14 in the illustrated embodiment, is limited. In this manner, duringinstallation of the connector 10, the tube 12 should not rotate morethan about 90 degrees within the ferrule 16. Additionally, the materialsof the nut 14 and the ferrule 16 are preferably chosen so as to minimizea coefficient of friction between the nut 14 and the ferrule 16. Inthese ways, the ferrule 16, and thus the tube 12, is intended to remainsubstantially rotationally stationary with respect to the nut 14 duringinstallation and/or removal or the connector 10. By doing this, thepossibility of leaks at the connector 10 can be reduced. Also, byremaining relatively rotationally stationary, buckling, twisting, etc.of the tube 12 is reduced during installation of the connector 10. Thisallows control of tube 12 routing because the tube 12 will tend toremain within a predetermined area in a predetermined configuration.

The portion 42 has a distal end, adjacent to a positive stop or proximalend 54 of the portion 52, and a proximal end 60. The proximal end 60 ofthe portion 42 is insertable into the bore 20 in the nut 14 tofacilitate joinder of the ferrule 16 and the nut 14. At least one tuberetention member or element or barb 62 is disposed on an inner diametersurface of the portion 42 adjacent the proximal end 60. In theillustrated embodiment, the barb 62 is interrupted by the slots 56 onthe portion 42. Thus, two barbs 62 (FIG. 7) are formed diametricallyoffset on the inner surface of the portion 42 adjacent the proximal end60. In other embodiments, multiple barbs 62 may be located axiallyoffset along the inner surface of the ferrule 16. In still otherembodiments, the barbs 62 may comprise no-lead threads located on thesame surface of the ferrule 16. If a plurality of barbs 62 wereutilized, as in FIG. 1, then it is possible to retain the tube 12 with arelatively reduced diametrical bite into the tube 12 and acorrespondingly reduced reduction of the tube 12 inner diameter. In anycase, the barb 62 is intended to "bite" to a positively limited extentinto an outer surface of the tube 12. The interaction between the barb62 and the tube 12 reduces the likelihood that the tube 12 may be pulledaxially out of the connector 10 when installed. Preferably, the barb 62and the tube 12 interact sufficiently such that a force of more thanabout 5 pounds is required to remove the tube 12 axially from theinstalled connector 10. The barb 62 is constructed such that theretention force it applies to the tube 12 is not substantially affectedby material creep over time. Also, the barb 62 is supported by theentering portion 42 of the ferrule 16. The construction of the barb 62and the entering portion 42 reduce a normal force at a zone of contactbetween the ferrule 16 and the tube 12 by spacing the contact zone fromthe portion 40 of the ferrule 16.

The proximal end 54 of the portion 52 joins the portion 52 to theportion 42. The proximal end 54 of the portion 52 also cooperates withthe bearing surface 34 on the second or entering end 24 of the nut 14 topositively limit the extent of biting of the barb 62 into the tube 12.By positively limiting this extent, constriction of the inner diameterof the tube 12 is also limited positively. Specifically, contact betweenthe outer diameter surface of the entering portion 42 of the ferrule 16and the inner diameter surface of the reduced portion 44 of the nut 14forces the barb 62 into the outer diameter surface of the tube 12.However, because the inner diameter of the reduced portion 44 isconstant, the contact between the reduced portion 44 and the enteringportion 42 is limited. The extent of biting of the barb 62 into theouter surface of the tube 12 can be predetermined by appropriatelychoosing relevant diameters of the portion 44 of the nut 14 and theportion 42 of the ferrule 16.

Contact between the bearing surface 34 and the proximal end 54 limitsaxial movement of the ferrule 16 with respect to the nut 14. Theseelements combine to positively limit the extent to which the barb 62 maybite into the outer surface of the tube 12. Because this biting ispositively limited, constriction of the inner diameter of the tube 12 isalso positively limited. In some embodiments, the barb 62 does notconstrict an inner diameter of the tube 12 by more than about five percent. Contact between the bearing surface 34 and the proximal end 54 ofthe portion 52 of the ferrule 16 also provides the installer withfeedback indicative of completed installation of the connector 10 withina port 68 in a body 36. The contact between the bearing surface 34 andthe proximal end 54 also limits axial movement of the nut 14 relative tothe ferrule 16. Preferably, the contact is achieved upon rotation of thenut 14 with respect to the ferrule 16 by about one and one-quarterturns. This can reduce the possibility of over-tightening of theconnector 10, thereby further reducing the probability of a leak.

The portion 52 of the ferrule 16 also has a distal end 64. The distalend 64 is intended to engage a base 66 of a port 68 in the body 36, asshown in FIG. 7. At least one barb 70 is located on an inner diametersurface of the portion 52 adjacent the distal end 64. In the illustratedembodiment, two barbs 70 are located offset diametrically on the portion52. The barb 70 is constructed to retain the seal 18 (FIG. 4) with theferrule 16. Specifically, the barb 70 has a configuration whichcomplements the configuration of a groove 72 on the seal 18. The groove72 is annular in the illustrated embodiment, but may be discontinuous inother embodiments. Cooperation of the barb 70 on the ferrule 16 and thegroove 72 in the seal 18 forms a snap fit.

The seal 18 itself has a proximal end 74 and a distal end 76. Theproximal end 74 engages a stepped interior surface of the ferruleadjacent the junction of the portion 42 and the portion 52. The seal 18is substantially cylindrical and has an axial bore 78 for accepting thetube 12. Accordingly, the diameter of the bore 78 is chosen such thatthe seal 18 fluid-tightly engages the outer surface of the tube 12without causing substantial constriction of the inner diameter of thetube 12. In some embodiments, the hardness of the material comprisingthe seal 18 and the area of contact between the seal 18 and the tube 12is predetermined such that the inner diameter of the tube 12 is notconstricted by more than about 5 per cent.

The seal 18 has an axial length predetermined such that the distal end76 of the seal 18, in a "rest" condition shown at the bottom, as viewed,of FIG. 7, extends beyond the distal end 64 of the portion 52 of theferrule 16. The distal end 64 of the seal 18 engages the base 66 of theport 68 upon installation of the connector 10. As the connector 10 isinstalled, the seal 18 is deformed, as shown at the top, as viewed, ofFIG. 7, to reduce the possibility of a leaky connection.

The following discussion further defines a preferred embodiment of theconnector 10. It is to be remembered that these materials and dimensionsare provided for clarity of understanding and are illustrative only.Other materials and dimensions are also possible. For instance, metaltubing can be accommodated by appropriately choosing materials for thenut 14 and the ferrule 16. Also, the compatibility of the connector 10is substantially independent of the inner diameter of the tube 12.However, the connector 10 is dependent on the tube 12 outer diameter.

One embodiment of the connector 10 is intended to mate with a 1/4 28 UNFplanar bottom port and a tube 12 having an outer diameter of about 0.10inches and an inner diameter of about 0.04 inches. However, other portsand tube dimensions are possible. The tube 12 may be made of a suitablepolymer, such as PTFE, HDPE and the like. The nut 14 is formed from asuitable polymer, such as an acetal and the like. The nut 14 may beformed by injection molding, machining and the like. The nut 14 is about0.7 inches long. The knurled portion is about 0.3 inches long and thethreaded portion is about 0.4 inches long. The beveled surface 30 on thefirst end 22 on the nut 14 defines an angle of about 45 degrees withrespect to the axis of elongation of the nut 14. The inner diameter ofthe tube engaging portion 48 is about 0.104 inches. The inner diameterof the reduced portion 44 is about 0.13 inches and of the enlargedportion 40 is about 0.16 inches. The portion 44 has an axial length ofabout 0.1 inches and the portion 40 has an axial length of about 0.15inches. The angles defined by the beveled surfaces 46 and 50 measureabout 30 degrees with respect to an axis of elongation of the nut 14.

The ferrule 16 is made of a suitable polymer, such as nylon, preferablyglass filled (about 15 to 33%) nylon. It is remembered that thematerials forming the nut 14 and the ferrule 16 are chosen such that acoefficient of friction between them is minimized. The ferrule 16 isabout 0.35 inches long. The outer diameter of the portion 52 is about0.2 inches, while its inner diameter is about 0.16 inches and its lengthis about 0.14 inches. The barb 70 is about 0.04 inches in axial lengthand two barbs 70 diametrically offset define a diameter between them ofabout 0.13 inches. The entering portion 42 defines an inner diameter ofabout 0.11 inches and the slot 56 is about 0.05 inches wide. The barbs62 which grip the tube 12 define a diameter between them of about 0.1inches in a rest condition. The barbs 62 are about 0.018 inches in axiallength.

The seal 18 is made of a suitable elastomer, such as a fluorocarbonrubber and the like. Elastomers are preferable because they canaccommodate larger dimensional variances among the tube 12, the seal 18,ferrule 16 and port 68. Also, elastomers can accommodate configurationchanges due to movement of materials comprising the connector 10, thetube 12 and/or the body 36 over time. In some embodiments, the seal 18,as well as the tube 12, may be in contact with fluid. Therefore, thematerial comprising the seal 18 should be compatible with the fluidconveyed in the tube 12. In one exemplary embodiment, VITON™ (Du Pont)can satisfy these requirements. The seal, in an undeformed state,defines an inner diameter of about 0.08 inches and an outer diameter ofabout 0.14 inches.

With the structure of the connector 10 being thusly described, a methodof making a connection or installation of the connector 10 will now bediscussed in detail. Further structural specifications may be explainedwith reference to the following discussion. Also, it is to be rememberedthat removal of the connector 10 may be effected by reversing the orderof the below described steps.

To begin installation, the installer prepares the tube 12. Asubstantially planar surface is made at the end 32 of the tube 12. Then,the members comprising the connector 10 are threaded onto the tube 12.First, the nut 14 is slid over the end 32 of the tube 12 such that thetube 12 enters and passes through the bore 20. Then, the ferrule 16 isslid over the end 32 of the tube 12. Finally, the seal 18 is applied tothe end 32 of the tube 12. In an exemplary construction, the end 32 ofthe tube 12 is substantially flush with the distal end 76 of the seal18. In this manner, after installation, a substantially smoothtransition will be formed between the tube 12 and the body 36. Thissmooth transition can reduce the probability of pressure loss, airentrapment, etc. at the tube 12/body 36 interface. If the end 32 of thetube 12 were to extend beyond the distal end 76 of the seal 18, thenforces generated during installation between the end 32 of the tube 12and the base 66 of the port 68 in the body 36 can cause the tube 12 toshift axially with respect to the seal 18 such that the above-describedalignment of end 32 and end 76 is achieved.

Because of diametric interference between the outer surface of the tube12 and the inner surface of the seal 18, the seal 18 remains in place onthe end 32 of the tube 12. The installer moves the ferrule 16 towardsthe seal 18 and the end 32 of the tube 12 such that the barb 70 on thedistal end 64 of the portion 52 of the ferrule moves into the groove 72on the seal 18. At this point the seal 18 and the ferrule 16 areoperatively coupled. In other embodiments the ferrule 16 and the seal 18may be integral, formed from the same materials or from differentmaterials.

The installer then moves the nut 14 towards the ferrule 16 and the seal18 by gripping the knurl 28 and applying appropriate force. The enteringportion 42 of the ferrule 16 moves into the portion 40 of the nut 14.Then, the installer moves the connector 10 and the tube 12 into the port68 in the body 36.

As the connector 10 enters the port 68, the mating structures or threads38 on the outer diameter surface of the nut 14 matingly engagecomplementary mating structures or threads 80 on the port 68. Theinstaller applies appropriate force or torque to the nut 14 such thatthe nut 14 advances axially towards the base 66 of the port 68 under theinfluence of the threaded engagement between threads 38 and threads 80.

As the nut 14 moves axially towards the base 66, the proximal end 60 ofthe portion 42 of the ferrule 16 moves adjacent the portion 40 of thenut 14. Upon sufficient axial movement of the nut 14 and when the distalend 64 of the ferrule 16 engages the base 66 of the port 68, asdiscussed below, the proximal end 60 of the portion 42 of the ferrule 16engages the beveled portion 50 on the nut 14. The inclination of theportion 50 directs the proximal end 60 and the entering portion 42 ofthe ferrule 16 into the reduced portion 44 of the nut 14.

As the nut 14 moves axially towards the base 66 of the port 68, thedistal end 76 of the seal 18 contacts the base 66. Because of thiscontact, the seal 18 changes from an undeformed condition, shown at thebottom, as viewed, of FIG. 7, to a deformed sealing condition, shown atthe top, as viewed, of FIG. 7. The seal 18 deforms to fluid-tightly sealthe interface between the end 32 of the tube 12 and the base 66 of theport 68. The seal 18 approaches its fully deformed condition as thedistal end 64 of the portion 52 of the ferrule 16 contacts the base 66.Contact between the distal end 64 and the base 66 assists in positivelylimiting deformation of the seal 18 to a substantially annular regionbetween the outer diameter surface of the tube 12 and the inner diametersurface of the portion 52 of the ferrule 16.

The distal end 64 of the ferrule 16 engages the base 66 of the port 68.The ferrule 16 does not move further axially towards the base 66.Rotation of the nut 14 after the distal end 64 engages the base causesthe entering portion 42 of the ferrule 16 to move further into theportion 44 of the nut 14. Engagement of the entering portion 42 with thereduced portion 44 causes the entering portion 42 to flex radiallyinwardly. The slot 56 allows for this flexing by permitting the distancebetween the sections 58A and 58B to be reduced. The sections 58A and 58Breduce contact between the nut 14 and the ferrule 16 which might causethe ferrule 16 to rotate conjointly with the nut 14. Thus, the tube 12and the ferrule 16 remain substantially rotationally stationary withinthe port 68 as the nut 14 threadibly rotates within the port 68.

As the entering portion 42 flexes, the barb 62 bites into the outerdiameter surface of the tube 12. The distance through which the barb 62bites into the tube 12 is predetermined by the preselected differencesbetween the outer diameter of the entering portion 42 of the ferrule 16and the inner diameter of the portion 44 of the nut 14. Furthermore,upon sufficient axial movement of the nut 14 with respect to the ferrule16 within the port 68, the proximal end 54 of the portion 52 of theferrule 16 contacts the bearing surface 34 on the second end 24 of thenut 14. This contact provides the installer with feedback indicative ofa sufficiently tight connection being made by the connector 10. Contactbetween the end 54 and the surface 34 also positively limits the extentof biting of the barb 62 into the outer diameter surface of the tube 12.Specifically, the contact between the end 54 and the surface 34positively limits the entering portion 42 of the ferrule 16 from axiallyadvancing towards portions of the nut 14 having an inner diametersmaller than the inner diameter of the portion 44 of the nut 14. Byproviding these positive limits, the fluid-tight seal provided by theconnector 10 is independent of the torque or installing force applied.Thus, the connector 10 will not be overtightened and the tube 12 willnot be excessively constricted.

Once the connector 10 has been installed in this fashion, it is possibleto remove or disassemble the connector 10 from the port 68 in the body36 by reversing the above-discussed method steps. Because the connector10 is installed without a tool and is not overtightened, viz. it is madeonly "finger-tight" (about 5 to about 50 oz.in.) within the bore 68, itcan be removed without the need of tools. Also, because the seal 18grips the end 32 of the tube 12, the ferrule 16 and the nut 14 shouldnot become disassociated from the tube 12 upon removal of the connector10 from the port 68. This reduces the probability of loose parts thatmay be lost. Preferably, the connector 10 has sufficient structuralintegrity to withstand about 50 cycles of installation and removalwithout replacement.

By connecting the tube 12 to the port 68 in the body 36 in this fashion,a number of benefits can be realized. A smooth transition may beprovided from the tube 12 to the body 36, thereby reducing possiblepressure or fluid loss, as well as air entrapment, at the connection.The nut 14 preferably is rotated by no more than one and one-quarterrevolutions during installation. No leaks should be present at theconnection, and the connector 10 and the tube 12 within the connector 10should be able to withstand internal pressures of about +45 psig toabout -10 psig. Given the materials discussed above, the connector 10should be able to withstand temperatures substantially within the rangeof about 2 to about 45 degrees Celsius.

Because of the construction of the nut 14 and the ferrule 16, theconnector 10 should be able to withstand a force of about 5 poundsintended to pull the tube 12 out of the connector 10 when installed. Thetube 12 should not rotate more than about 90 degrees as the nut 14 isrotated within the port 68. Flexing of the tube 12 proximally of theconnector 10 should not cause any leaks at the connector 10.

While the embodiment of the invention shown in the Figures illustratesone connector 10 and one single tube 12, it is to be noted that theembodiments of the invention do not have to be so limited. For instance,it is possible to have multiple connectors 10 operatively associatedwith each other by a carrier or manifold. The connectors 10 may beattached to or formed integrally with the carrier. Instead of threads,an outer diameter surface of the associated nuts 14 may include othermating structures, such as structures sufficient for generating aninterference fit between the nuts 14 and the ports 68. The connectors 10are press fitted into the ports 68, mimicking the above-describedinstallation steps. The carrier may be maintained in place by a suitablebracket, clamp and the like. Thus, multiple connectors 10 may besimultaneously installed into multiple ports 68 by manipulation of thecarrier. In still other embodiments, all parts comprising the connector10 may be molded integrally, possibly with a retention mechanism, suchas a screw detent and the like. Furthermore, the first end 22 of the nut14 may be provided with an application force or torque limitingmechanism, such as a clutch assembly and the like.

What is claimed is:
 1. A method for forming a connection between a tubeand a port, the method comprising the steps of:(a) providing a tubehaving first and second ends; (b) providing a first member having firstand second ends, an outer circumferential surface having matingstructure thereon, and a bore extending therethrough, said bore beingdefined by:(i) a first diameter portion located between said first andsecond ends; (ii) a second diameter portion located between said firstdiameter portion and said second end; (iii) a vertical wall joining saidfirst diameter portion to said second diameter portion; (iv) a thirddiameter portion between said second diameter portion and said secondend; and (v) an inclined portion joining said second diameter portion tosaid third diameter portion, wherein the diameter of said first diameterportion is greater than that of said second diameter portion and thediameter of said second diameter portion is greater than that of (c)providing a second member having first and second ends and a boreextending therethrough, with a retention member extending inwardly fromsaid bore at said second end, and also having an outer surface definedby first and second diameter portions with a vertical wall joining theseportions to one another; wherein said second diameter portion has adiameter greater than that of said third diameter portion of said firstmember, and less than that of said second diameter portion of said firstmember; (d) providing a seal having first and second ends and a boreextending therethrough; (e) providing a port having a bore defined bymating structure, and an end wall extending perpendicularly to saidbore; (f) locating said seal partially within said bore of said secondmember at said first end thereof; (g) locating said second memberpartially within said first member at said first end thereof; (h)locating said tube at least partially within said first member, saidmember and said seal, such that said first end of said seal extends fromsaid first end of said second member, and said first end of said secondmember extends from said first end of said first member; (i) insertingsaid tube, said seal, said second member and said first end of saidfirst member into said bore of said port, such that said matingstructure of said first member engages said mating structure of saidport; (j) moving said first member further into said bore of saidportion by continually engaging said mating structure of said firstmember with said mating structure of said port, thereby causing:(i) saidinclined portion and said third diameter portion to deflect said seconddiameter portion of said second member inwardly such that said retentionmember engages said tube; and (ii) said vertical wall of said firstmember to abut said vertical wall of said second member, such that saidfirst member drives said second member, said seal and said tube againstsaid end wall, whereby said seal deforms against said end wall and formsa leak-proof joint between said tube and said port.
 2. The method asdefined in claim 1, wherein the step of abutting said vertical wall ofsaid first member with said vertical wall of said second memberpositively limits the engagement of said retention member with saidtube.
 3. The method as defined in claim 1, wherein the step of abuttingsaid vertical wall of said first member with said vertical wall of saidsecond member provides feedback indicative of completion of theconnection.
 4. The method as defined in claim 1, wherein the step ofdeforming said seal against said end wall and the step of engaging saidretention member with said tube, each constricts an inner diameter ofsaid tube by no more than about five per cent.